In addition to an almost uniformly fatal prognosis for its victims, AIDS often results in ocular complications frequently leading to blindness. We have planned a natural history observational cohort study of retinal microvascular changes (including cotton wool spots) in patients who are asymptomatic but HIV antibody positive, patients with advanced ARC, and patients with AIDS. We will test the hypothesis that the occurrence of cotton wool spots and other retinal microvascular changes are indicators of progression of HIV infection and indicators for development of cytomegalovirus (CMV) retinitis. We also have developed a proposal for a randomized prospective therapeutic trial of two drugs (ganciclovir vs foscarnet) in the treatment of CMV retinitis, the most common retinal infection in AIDS and the leading cause of blindness in patients with HIV infection. The Fundus Photograph Reading Center is developing a photographic protocol including a combination of the seven standard stereoscopic 30 degrees fields to document the posterior pole and adjacent retina, as described by the Diabetic Retinopathy Study, and an adaptation of the matrix of wide-angle views (preferable 60 degrees fields) to document the majority of the post-equatorial fundus, as described by the Silicone Study. Photographs will be evaluated at the Reading Center for the Presence and severity of noninfectious AIDS retinopathy (including cotton wool spots, hemorrhages, and micoraneurysms) and infectious retinopathy, particularly CMV retinitis. We have planned development of a standardized grading protocol that entails comparison of the photographs being graded with selected standard photographs in order to quantitate lesions, and also utilizes direct measurement of some lesions and their change from baseline.